The invention relates to a tip, more in particular a ground displacement tip for use during a ground displacement operation for a foundation pile. The invention also relates to a method for manufacturing such a tip. Furthermore, the invention also relates to a ground displacement assembly which makes use of such a tip which is attached to the bottom end of a pipe of the ground displacement assembly during a ground displacement operation.
A method for arranging a foundation pile into the ground is known, for example, from EP1412584 and EP1564367. With this method, a hollow steel pipe having a tip at the bottom, more in particular a ground displacement tip, is entered into the ground to the desired depth by a foundation machine. By entering the pipe having the ground displacement tip at the bottom, an opening is formed in the ground for entering or forming a foundation pile. With such a method, for example, the pipe of the foundation machine together with the ground displacement tip is rectracted out of the opening in the ground, wherein the foundation pile can be formed in situ by entering, for example, a steel pipe which is filled with concrete.
It is clear that alternative methods exist wherein use is made of such a tip, more in particular a ground displacement tip, as known, for example, from U.S. Pat. No. 4,623,025 and EP0855489. Such a cast-iron tip is removably attached to the bottom end of a pipe of the foundation machine during a ground displacement operation. The tip is preferably configured as a cast-iron structure, since this facilitates efficient production of a suitable design, in particular when, for example, spiral-shaped ribs are arranged on the surface of the tip body of the tip to achieve an efficient ground displacement operation. In order to couple the tip removably to the bottom end of the pipe of such a ground displacement assembly, the tip is at its top end provided with ridge-shaped structures which couple in corresponding recesses at the bottom end of the pipe. According to this method, the pipe of the ground displacement assembly is entered into the ground layer, together with the tip at its bottom, during a ground displacement operation. After the ground displacement assembly has been entered into the ground layer to the desired depth, concrete is supplied in order to form a concrete foundation pile which is poured in situ. While forming this foundation pile which is poured in situ, the pipe of the ground displacement assembly is removed from the ground layer by the foundation machine, without the tip. The removable tip remains in the ground layer at the bottom side of the concrete foundation pile.
From EP1412584 and EP1564367 embodiments are known of such a ground displacement tip with a tip body to which several spiral-shaped ribs which protrude from the tip body are arranged. In order to improve displacement of the ground during a ground displacement operation and also to improve the mixing with liquid means, such as, for example, concrete slurry, cement, water, etc., which are supplied at the height of the tip during a ground displacement operation, use is made of several protrusions or teeth arranged on the spiral-shaped ribs which extend downwards along the axial drilling direction. However, these teeth or protrusions are subjected to very high loads when the screw movement is being performed during a ground displacement operation. As a result thereof, in particular the protruding teeth are subject to the risk of breaking or damage during the ground displacement operation for a foundation pile, in particular when such a ground displacement tip is applied for a ground displacement operation in relatively hard ground layers.
It is clear that ground drills or ground displacement assemblies are further known which use a tip with a tip body to which, for example, hard-metal or ceramic teeth, bits or cutting platelets are attached. The manufacturing of such hard-metal or ceramic teeth requires complicated and expensive manufacturing techniques, wherein, for example, also the freedom regarding the design of the teeth is limited to, for example, conical teeth. Furthermore, in order to attach such teeth to a tip body, it is required to make use of specific associated attachment elements, for example, which have to be arranged on or in the tip body for attaching such teeth. It is clear that arranging such teeth to the tip body is a complicated and often labour-intensive, manual task, which requires to match the various tolerances related to the tip body, the attachment element, the teeth, etc. accurately to each other in order to guarantee a high-quality attachment. Manufacturing such a tip thus requires complicated, expensive manufacturing methods, as a result of which such a tip is not suitable for use in ground displacement operations for a foundation pile, in particular when, for example, the tip is left behind in the ground layer as part of a foundation pile assembly. Furthermore, the attachment elements for the attachment of such teeth to the tip body lead to a risk of teeth breaking when these are subjected to high loads during a ground displacement operation.